Phylogeography Of Iris Loczyi Kanitz

Iris loczyi Kanitz,belonging to Iris subg.Limniris sect.Limniris(Iridaceae),is mainly distributed in meadows,grasslands,and desert gravels in the Qinghai-Tibet Plateau and Central Asia.I.loczyi has strong adaptability to the climatic conditions in high-cold and high-altitude areas,and can survive the harsh climatic environment affected by glacial movement.It is a good material for studying the genetic diversity and genetic geographic patterns of the Qinghai-Tibet Plateau and adjacent areas.Further explore the impact of Quaternary climate fluctuations on the current plant distribution pattern and population evolution history on the Qinghai-Tibet Plateau,and provide scientific basis and reference for the biodiversity conservation of Iris L.plants in the Qinghai-Tibet Plateau.In order to reveal the genetic diversity and spatial distribution pattern of I.loczyi,this paper analyzed the cpDNA fragments and SSR primers of 149 individuals in 15 populations of I.loczyi.The results are as follows:Based on 5 cpDNA fragments(trn S-trn G,trn S-trnf M,rpl20-5'-rps12,psa I-acc D,trn H-pbs A),a total of 108 single nucleotide variants were obtained,meanwhile 10 haplotypes were detected.Haplotype diversity(Hd = 0.820)and nucleotide diversity(? = 0.00981)had high levels.1.At the species level,the genetic differentiation index of I.loczyi Fst> 0.25(0.951),indicated that the genetic differentiation between populations was more significant.2.Based on the analysis of the haplotype network diagram,it could be seen that there were 7unique haplotypes in the population distribution in the Qilian Mountains,3 unique haplotypes in the southern Tibet valley,and the Qilian Mountains were the genetic diversity center of I.loczyi.3.The NJ tree and Bayesian tree analysis results constructed based on cpDNA fragments showed that I.loczyi clustered into three branches,among which the population XS in the Qilian Mountains clustered into one branch,meanwhile the other populations in the Qilian Mountains clustered into one branch;southern Tibet The four populations in the valley clustered into one group.4.Samova's analysis results showed that all populations of I.loczyi clustered into 4 groups.Compared with the phylogenetic results,it could be seen that the populations of JC in the southern Tibetan valley clustered into one group alone.5.AMOVA analysis results showed that the genetic variation of I.loczyi mainly occured in between groups(91.14%)and between populations(92.11%).6.The results of neutral test and mismatch distribution analysis showed that I.loczyi had not experienced a large-scale expansion event in history.A total of 163 alleles were detected based on 7 SSR markers.Each locus contained23.29 alleles on average,the average expected heterozygosity of the population(He = 0.699)was greater than the average observed heterozygosity(Ho = 0.689),cross coefficient Fis> 0(0.014),indicating that I.loczyi had high genetic diversity.1.The average genetic differentiation index(Fst)was 0.250,which indicated that the level of genetic differentiation among populations was moderate.2.The structure cluster analysis results showed that I.loczyi clusters into three clusters,among which the population XS in the Qilian Mountains clustered into one category,the other populations in the Qilian Mountains clustered into one category,and the populations in the southern Tibet valley clustered into one category.3.AMOVA analysis results showed that the genetic variation of I.loczyi mainly came from within the population(80.82% and 74.96%).4.The UPGMA tree analysis result was consistent with the phylogenetic relationship constructed based on cpDNA.Based on all the analysis results,I.loczyi may have multiple refuges during the last glacial maximum.The Riyue Mountain in the east of the Qilian Mountains,the Chaka Basin surrounded by Qinghai Nanshan and Ora Mountains may be a glacial refuge for I.loczyi;in addition,The eastern part of the southern Tibet valley may be another glacial refuge for I.loczyi,which conforms to the northern refuge model.In this paper,we studied the genetic diversity and genetic structure of I.loczyi,and determined the location of the ice age refuge.In addition,this study provides a theoretical basis for exploring the phylogeography of species in the Qinghai Tibet Plateau and its adjacent areas,and provides a theoretical basis for further understanding the evolutionary history and Germplasm Resources Protection of Iris L.